Soybeans have long been recognized as a good source of food proteins, and soybean protein materials are coming into substantial use either in place of other natural foods or in combination with such other foods. The soybean proteins are nutritious, can be made available in large quantities, and are economically produced. There is great incentive to the preparation of soybean protein materials, particularly for use inplace of or as extenders in combination with meats. The soybeams are grown directly from the soil and in this respect have a great economic advantage over meats which are obtained by feeding vegetable foods to livestock animals and then slaughtering the animals.
In the development of soybean protein materials for use in place of or along with meats three principal obstacles have confronted the art. One of these is flavor, and another is odor, each of which is characteristic of soybean materials and which is unnatural and unpleasant in most foods, and the third obstacle is the color of the soybean protein materials which is unnatural to the meats being simulated, and which is also unpleasant particularly when the soybean materials are used along with meat. The objectionable flavor and odor problems have now been substantially disposed of through improvements in the preparation of the protein materials from the soybean source, but the color problem has persisted.
Many commercial processors of soybean products now make and sell a soybean protein material which is satisfactory as to flavor and odor and which may take one of several specific forms. Some specific products of this type have been treated to give the products a texture similar to the texture of meat and others are in powder, granular or flake form. These products are available in their texturized form, as a flour, or as having various concentrations of protein. The form known as isolate contains of the order of 90% protein. None of them, to my knowledge, is quite satisfactory in color for use in place of or along with meat. One such product which is sold under the trade designation "Supro 50" is quite satisfactory as to odor and texture, but is tan in color and because of its color is quite incompatible with meat such as hamburger or sausage. When such tan colored protein material is mixed in ground uncured meat the mixture has a mottled, unattractive appearance. Even though it could be possible to discover a coloring material which would simulate the color of a meat such as raw hamburger, this would not be expected to solve the problem because of the expectation that it would create a different mottled appearance upon the cooking of the meat. The uncured meat turns a grey-brown color when cooked, but the added coloring material would be expected to retain its same color resulting in a very unsatisfactory color effect. On the other hand, if a coloring material could be found which would simulate the brown color of cooked uncured meats it would still be unsatisfactory because of the mottled effect in the raw meat. Therefore, it is necessary not only that the soybean protein material assume a color like the color of the raw meat it is to be placed with, but also that its reaction to the heat of cooking be similar to that of the meat.